Thermionic tube compensator for aerials



May 10, 1938. Gt DE MONGE 2,116,696

THERMIONIC TUBE COMPENSATOR. FOR AERlALS Filed Jan. 24, 1936 Patented May 10, 1938 UNITED STATES Search PATENT FFICE THERDIIONIC TUBE- COMPENSATOR FOR AERIALS Gerard de Monge, Flostoy, Belgium Application January 24, 1936, Serial No. 60,712 In Belgium January 24, 1935 8 Claims.

The invention essentially consists in applying thermionc valve circuits, including, for example, triodes and the like, for the suppression or reduction of interference.

It is known that a great deal of interference is of industrial origin reaching particularly the down-lead of the aerial but having less effect upon the aerial proper, especially when the latter is high.

Diierent systems have been proposed for screening or shrouding the down-lead of the aerial or to counter-balance the action of this down-lead in order to reduce the eiect of interference.

It has been proposed notably to screen the down-lead, but that could not be realized Without a considerable loss of power, resulting in magnetic loss due to capacity between the conductor Wire and earth.

The counter-balance of the down-lead by influence of a second parallel wire admits less loss by capacity, but it necessitates the transformation of the current into magnetic ux, which also could not be done without considerable loss.

On the other hand, compensating windings cannot be used without the effects Qf resonance on certain wave-lengths impairing their efciency.

According to the invention, a system of compensation or counter-balance is realized which is eiective with minimum loss of eiciency and without having recourse to any inductive action by using in the first stage of the receiver an ordinary thermionic valve ampliiier circuit arranged in such a way as to be operable at the same time by its grid and by its cathode, whereby one of the collectors, for example the aerial, is connected to the grid, while the other, for example the down-lead compensator, is connecte to the cathode.

As it is known, all the variations of the anode current of a valve circuit (triode or the like) are functions of the voltage relation between the grid and the cathode, and it is evident that if similar charges reach both electrodes simultaneously, they do not produce any variation of the plate current so long as they are of the same small magnitude with respect to the permanent anode voltage, which is obviously the case of high frequency currents gathered by the aerial.

To realize the dual control of the valve circuit, the cathode must in relation to the return point of the current, for instance the earth, have a high impedance, and, moreover, between the grid and (Cl. Z50-20) earth there should be a resistance of the same magnitude.

An appropriate potential can be given to the grid in such a way that the valve is in good working condition irrespective of the potential 1 which will be applied to the cathode from the resistance between this latter and the anode current return point, e. g. the earth.

The grid and the cathode resistances can be so regulated or arranged as to give to each branch of reception (the aerial on the one hand and the down-lead compensator on the other) appropriate values for the achievement of the best result.

In order to balance not only the interference collected by the down-lead of the aerial, but also the interference collected by the uncompensated part of the aerial, the control for the secondary collector or compensator can be regulated to a greater extent than that of the aerial.

These regulations can be accomplished without causing alteration to the value of grid potential relative to the cathode and vice versa in such a way as to leave these at the most advantageous level for permitting control of the input to one of these two electrodes.

A simple way of realizing this condition is to make the impedance determining the amplitude of the approaching potentials variable by means of a small condenser operating by its reaction without influencing the potential between the cathode and the grid.

'I'he regulation oi the extent of action can be established, either by constant means or by a part of the constant impedance and a variable part, which can operate in a differential sense upon both elements, for example by disposing resistances in the cathode and grid circuits, and in having between these resistances a potentiometer the sliding contact of which can be connected to earth.

The means for controlling the impedances can be adjusted but it is preferable that they are aperiodic in order to avoid any trouble which might be caused by resonance.

In the accompanying drawing, forming part of the specication and in which like numerals are employed to denote like parts throughout the same:

Fig. 1 is a circuit diagram showing the application of the invention to the neutralization of an aerial down-lead;

Fig. 2 is a circuit diagram representing a modication of the circuit shown in Fig. 1;

Fig. 3 is a circuit diagram illustrating yet a further modification.

In Fig. 1 the aerial l, situated at a considerable height in a region relatively sheltered from .the industrial interference, is connected to the grid G of the valve T. This aerial is also connected to earth through the medium of the rheostat 2.

'I'his rheostat 2 is connected to the grid terminal and so provides for regulation of the grid voltage. A second wave collector 3 running alongside the down-lead 8 of the aerial, but not connected to it, feeds the cathode C of the same valve T. A rheostat 4 similarly allows the amplitude of the gathered potentials to be regulated by varying the resistance between the cathode C and earth. The plate P of the same valve T receives the high tension current by the choke 5 and transmits to the point l, through the condenser 6, the amplified high frequency currents resulting from the variations of the relative potentials between the grid G and the cathode C.

It will be understood that when the equal charges of the same sense arrive simultaneously on the grid G and the cathode C, the valve T does not work, and that no variation of current is noticeable at the point 1. In consequence none of the charges gathered simultaneously by the down-lead 8 of the aerial l and by the auxiliary down-lead or compensator 3 will be transmitted to the point l and will thus be eliminated in the subsequent stages of the receiver. The charges collected by the uncompensated part of the aerial I, reaching the grid G only, cause the valve T to operate in the ordinary way and transmit ordinary current variations to the point l.

It is conceivable that instead ci a triode, any other convenient form of valve may be used, e. g. a screen-grid, pentode or the like.

The circuit represented in Fig. 2 is such that the regulation of the impedances determining the balance of the two operating electrodes can be realized without inuencing the potential given to the grid with reference to the cathode. The grid G and the cathode C are each connected to the earth by fixed resistances 2 and 4 respectively and by the variable condensers 9 and I0 respectively which allow the variation of the total impedance constituting a point of balance of these electrodes as regards high frequency currents without influencing their xed potential.

In the arrangement shown in Fig. 3, the circuits of the electrodes G and C each contain a xed resistance 2 and 4 respectively and a differential control in the form of a potentiometer Il of which the sliding contact is connected to earth.

What I claim is:-

1. In a radio receiver, a triode valve including a cathode element and a grid element, and an effective high-frequency impedance interposed between the cathode element and a neutral point of the receiving circuit, a main aerial connected to one of said elements, a secondary aerial connected to the other of said elements, and a high frequency impedance between the grid element and the neutral point of the receiving circuit.

2. In a radio receiver, a triode valve including a cathode element and a grid element, and an effective high-frequency impedance interposed between the cathode element and a neutral point of the receiving circuit, a main aerial connected to one of said elements, and a secondary aerial connected to the other of said elements, and a high-frequency aperiodic impedance between the grid element and the neutral point of the receiving circuit.

3. In a radio receiver, a triode valve including a cathode element and a grid element, and an effective high-frequency impedance interposed between the cathode element and a neutral point of the receiving circuit, a main aerial connected to one of said elements, a secondary aerial connected to the other of said elements, and a highfrequency impedance between the grid element and the neutral point of the receiving circuit, and means for varying said irnpedances.

4. In a radio receiver, a triode valve including a cathode element and a grid element, and an effective high-frequency impedance interposed between the cathode element and a neutral point of the receiving circuit, a main aerial connected to one of said elements, and a secondary aerial connected to the other of said elements, means for controlling the degree of action of the secondary aerial on the receiver with a voltage higher than that of the main aerial for compensating not only the interference collected in the zone common to the two aerials but also the interference collected by the part not common to the main aerial.

5. In a radio-receiver, a thermionic tube including a cathode element and a grid element, an effective high-frequency impedance interposed between the cathode element and an earth equivalent point of the receiving circuit, a main aerial connected to one of said elements and a second aerial connected to the other of said elements, and said second aerial extending in a spaced relation along the main aerial.

6. In a radio receiver, a thermionic tube including a cathode element and a grid element, an effective high frequency impedance interposed between the cathode element and a neutral point of the receiving circuit, a main aerial connected to one of said elements, a secondary aerial connected to the other of said elements and extending adjacently along the main aerial, and means for controlling the amplitude of high frequency potentials applied to said cathode and grid elements.

'7. In a radio receiver, a thermionic tube including a cathode element and a grid elemreniguan effective high frequency. impedacewint between the cathode element and. a neu mal of the receiving circuit, a mainq aerial coni'ietdI to one of said elements, a secondary aerialwgonnected to the other of saiiu'elements'and exigenci--- ing along a portion of the main aerial in a spaced relation, and independent means fci controlling the amplitude of high' frequency potentials applied to said cathode 4and grid'elen'ientsfMv u 8. In a radio receiver, a thermionic tube including a cathode element and a grid element, an eifective high frequency impedance interposed between the cathode element and a neutral point of the receiving circuit, a main aerial connected to one of said elements, a secondary aerial connected to the other of said elements and extending in a spaced relation along the main aerial, and means for controlling the amplitude of high frequency potentials applied to said cathode and grid elements comprising variable condensers.

GERARD DE MONGE. 

